water leaks from the map light

[Coldwaves]

2005 Pontiac Grand Prix base model. No sunroof.

Water leaks from the map light into the front cup holder. I saw a few thread that this is probably the Onstar Antenna since I don't have sun roof (I will test it later to confirm). From what I read in this forum, it seems loosen the antenna bolt, and put some silicone between the roof and rubber seal outside should work. But how do I loosen the bolt of the antenna? I took out the map light and can see the antenna bolt. But it is so hard to get a wrench there. Do I need to take down the headliner as well? Or will a smaller flexible head ratchet work here? Any advice is appreciated.

[ericspecullaas]

Yeah remove headliner

[Coldwaves]

Yeah remove headliner

Thanks! It is definitely easier to do the job with the headliner off. I will try without taking the headliner out to see if I can get it. If not, I will start looking at how to take off the headliner.

Sigh, I have so many little problems with my 05 GP. Maybe it is time for a change......

[spazzz]

Don't remove the headliner....Eric what are you thinking.

Get a Harbor Freight crows foot socket set. Not sure of the size but undoubtedly metric
I can't remember what I used....vice grips? 8" pliers?
FVck the on-star and clip the wire and stick a socket on it.

[Coldwaves]

Don't remove the headliner....Eric what are you thinking.

Get a Harbor Freight crows foot socket set. Not sure of the size but undoubtedly metric
I can't remember what I used....vice grips? 8" pliers?
FVck the on-star and clip the wire and stick a socket on it.

Thanks for pointing out the tool. I thought it is possible to do it without taking out the headliner but my ratchet is too big for the small space. It is obviously easy if headliner is off but I want to avoid the hassle of taking it out.

Am I correct that I only need to loosen the bolt? No need to take the antenna completely off the car, right?

Do you know how GM seal it out of factory? Is it just a rubber seal that is pulled tight against the roof by the bolt?

[spazzz]

Thanks for pointing out the tool. I thought it is possible to do it without taking out the headliner but my ratchet is too big for the small space. It is obviously easy if headliner is off but I want to avoid the hassle of taking it out.

Am I correct that I only need to loosen the bolt? No need to take the antenna completely off the car, right?

Do you know how GM seal it out of factory? Is it just a rubber seal that is pulled tight against the roof by the bolt?

Yes to all your questions.
It was 9 years ago when I did mine, it was easy and i didnt take the beadliner out.
I just cant remember what specific wrench i used

[Coldwaves]

Yes to all your questions.
It was 9 years ago when I did mine, it was easy and i didnt take the beadliner out.
I just cant remember what specific wrench i used

Thank you so much! I will probably try to fix it this weekend.

[Coldwaves]

I tested it today and confirmed that it is leaking from the OnStar antenna. I can see the rubber seal at the base of the antenna does not seal with the roof very tightly. I poured water near the antenna and can see water drips from the behind the bolt. Pouring water at other places does not cause any leaks. The bolt is a 10mm bolt. It is hard to reach there with a regular wrench and my ratchet needs an adapter to put on the 10mm sockets and that makes it too long to fit on the bolt through the map light. I will look for a smaller ratchet to try. I will update once I figure it out.

[Coldwaves]

I got it fixed. All I did is to take out the map light and to loosen the bolt that holds the antenna tight to the roof. Once the bolt is lose enough that I can pull the antenna up, I pour silicone seal at the base of the antenna outside. After that, I tight the bolt and clean the silicon seal that was squeezed out. It was pretty easy fix. Since then, the car does not leak any more. Loosening the bolt might be a little time consuming because it is at a strange angel but a little bit of patience should get it done. I had a small ratchet and get it done. The bolt is 10mm. I poured too much silicone and it starts dripping inside through the bolt inside to the headliner. You only just need a little bit to form a good seal.

Thanks everyone for the input and suggestions!